Histopathological and immunohistochemical studies of intracranial nervous-system tumours in four cattle.

Intracranial nervous-system tumours were diagnosed in three of 1092 bovine necropsy specimens submitted to the Department of Veterinary Pathology, Obihiro University between April 1983 and March 1996. A fourth case was a referral from the Department of Veterinary Pathology, Rakuno Gakuen University. Histopathological examination revealed four types of tumour: intracranial malignant peripheral nerve sheath tumour (MPNST), choroid plexus papilloma, differentiated fibrillary astrocytoma and anaplastic (malignant) astrocytoma. Immunohistochemically, the intracranial MPNST was strongly positive for S-100 protein and vimentin, and in places weakly positive for glial fibrillary acid protein (GFAP). The choroid plexus papilloma was strongly positive for epithelial membrane antigen (EMA), keratin, S-100 protein and vimentin, and positive for GFAP in places. The cytoplasm and fibrous component in the differentiated fibrillary astrocytoma were strongly positive for S-100 protein and GFAP. The anaplastic (malignant) astrocytoma was strongly positive for vimentin, S-100 protein and keratin in the cytoplasm and fibrous processes, and weakly positive for GFAP and EMA in places. Myelin basic protein (MBP) and synaptophysin showed a weak positive reaction in the marginal areas of the tumour.